CHARACTERIZATION OF NORMAL AND ALTERED FORMS OF DENTIN

牙本质的微观结构和性质是几乎所有 牙科修复手术 正常牙本质表现出变异， 结构和属性与位置，但在各种额外的 牙本质类型、龋性冠状牙本质和牙本质的改变形式 根牙本质是特别重要的。 它们是由至关重要的防御性 与改变组成的成牙本质细胞相关的机制， 硬度和渗透性。 这些改变的牙本质形式是重要的 用于牙本质粘结的基质。 因此，在牙本质粘附和 牙本质生理学需要对它们的基本 微观结构、组成和性能。 该项目将扩大 知识和技术开发的前期正常牙本质， 这两种重要的牙本质变异在许多 临床情况。 龋齿在牙本质中产生多层结构， 结构丧失、脱矿和矿化过度。 传统上 最深的改变层被称为透明牙本质，这是由于其改变的 折射率或硬度反映牙本质硬度的增加 由于矿化增加。 在某些情况下，透明 牙本质比正常牙本质软。 这表明不同的子类 的透明牙本质可能是由龋齿引起的，并建议使用 透明牙本质和硬牙本质作为可互换的术语， 正确. 牙根的硬化牙本质研究得少得多， 被认为是由于宫颈中的各种刺激过程而形成的 区域和整个根老化，即使在没有龋齿， 特征在于小管腔被额外的晶体堵塞 至少在宫颈病变中是耐酸的。 变更 尚未形成小管间牙本质。 显然有 关于这些改变的结构和性质的信息不足 牙本质及其特定区域。 要检验的中心假设是， 龋性牙本质和非龋性根面牙本质表现出重要的 结构、成分和性质的差异， 正常牙本质 我们将检验这一假设，并澄清结构和 这些改变形式的牙本质的性质通过十个特定的行为， 目标，五个与龋齿相关的目标和五个与science相关的平行目标 颈部和根部牙本质。 这些包括绘制改变的牙本质区域 包括X射线衍射分析（XTM）的矿物质含量、扫描电镜（SEM）、原子力显微镜（AFM）的结构、硬度 通过显微硬度和AFM纳米硬度（目的1，6）。 我们还将测试 假设改变的牙本质形式对 脱矿质并表现出渗透性的变化（目标2、6）。 的 假设管间区的组成和结构 矿物质被改变，而管周没有，将被测试， 用显微FTIR、AFM、SEM/EDS/WDS和TEM结合电子显微镜 衍射和PEELS（目标3，4）。 将进行类似的研究， 使用类似的方法对颈部和根部牙本质进行检查（目的8，9）。

Dentin microstructure and properties are determinants of nearly all operations in restorative dentistry. Normal dentin exhibits variation in structure and properties with location, but among the various additional dentin types, the altered forms of carious coronal dentin and sclerotic root dentin are particularly important. They result from vital defensive mechanisms associated with the odonoblasts which alter composition, hardness and permeability. These altered forms of dentin are important substrates for dentin bonding. Thus progress in adhesion to dentin and dentin physiology require a thorough knowledge of their basic microstructure, composition, and properties. This project will extend the knowledge and techniques developed ina th prior period for normal dentin to these two important variations of dentin which are encountered in many clinical situations. Caries produces a multi-layered structure in dentin with varying degrees of structural loss, demineralization and hypermineralization. Traditionally the deepest altered layer is termed transparent dentin, due to its altered refractive index or sclerotic dentin to reflect the increase in hardness due to increased mineralization. However, in some cases, transparent dentin is softer than normal dentin. This suggests that varying subclasses of transparent dentin could result from caries and suggests that the use of transparent and sclerotic dentin as interchangeable terms may not be correct. Sclerotic dentin of the root is much less studied, and is considered to form due to a variety of irritation processes in the cervical region and aging throughout the root, even in the absence of caries and is characterized by occlusion of the tubule lumen with additional crystals that are acid resistant, at least in cervical lesions. Alteration of the intertubular dentin has not been established. it is clear that there is insufficient information on the structure and properties of these altered dentins and their particular zones. The central hypothesis to be tested is that the structure of transparent carious dentin and sclerotic non-carious root dentin exhibit important structural, compositional, and properties differences as compared with normal dentin. We will test this hypothesis and clarify the structure and properties of these altered forms of dentin through conduct of ten specific aims, five related to caries and five parallel aims related to sclerotic cervical and root dentin. These include mapping zones of altered dentin including the mineral level by XTM, structure by SEM/EDS and AFM, hardness by microhardness and AFM nano-hardness (aims 1,6). We also will test the hypothesis that altered forms of dentin respond differently to demineralization and exhibit changes in permeability (aims 2,6). The hypothesis that the composition and structure of the intertubular zone mineral is altered, while the peritubular is not, will be tested for carious dentin using micro-FTIR, AFM, SEM/EDS/WDS and TEM with electron diffraction and PEELS (aims 3,4). Similar studies will be conducted for sclerotic cervical and root dentin using similar methods (aims 8,9).